The wiring for the rears would be for the sedan. They have rear speakers (I'm guessing the hatch doesn't).
You can get wiring adapters from most places that sell car audio. They basically plug into the factory loom and then plug straight into whatever brand of head unit you have. Obviously you have to get the right one to suit.
If you're not good with electronics, you'd be best spending the $20 or so on one of those. Otherwise, get in there with a multimeter or test light and figure out which is which. It shouldn't take more than five minutes. Then cut, solder and heatshrink as necessary. You only really need to figure out what wires the ignition and +12v is. I forget what colours they are on the factory loom.